The present invention is related to bearings for rotary machines and more particularly bearings of the type having pins as elastic elements and oil film dampers as damping elements. The bearings in accordance with the present invention are particularly adapted for use in high-speed rotary machines such as turbochargers, power recovery turbines, gas turbines, jet engines and steam turbines whose critical speed present problems.
FIG. 3 shows the construction of a typical conventional bearing for high-speed rotary machines. Reference numeral 21 designates a rotating shaft rotating at a high speed; 22, an inner race of a rolling bearing; 23, an outer race; 24, a ball (or a roller in some cases); 25, a casing of the outer race; 26, a pin; 27 and 28, locking nuts for locking the pin 26; 29, a seal ring; 30, a pin holder; and 31, a main body (a casing). The pin 26 is supported as a cantilever at its one end by the outer-race cage 25 while the other end is supported by the holder 30. Therefore the pin 26 receives any thrust load.
As described above, the conventional bearing needs the outer-race casing 25 so that the component parts are increased in number. Furthermore it is difficult to maintain a required accuracy. As a result, the conventional bearing has a low degree of reliability. Moreover, because the pin 26 is supported as a cantilever, an oil film thickness is not constant. Especially in the case of a roller bearing, the axis of the outer race 23 and the axis of the roller are not parallel with each other so that there arises a possibility that the roller contacts partially with the outer race 23. The pin 26 receives any thrust load so that its strength in the axial direction must be considerably high and consequently it is difficult to select a spring constant freely.
The present invention was made to overcome the above and other problems in the conventional bearings. According to the present invention, the number of component parts can be reduced to a minimum; a higher accuracy can be maintained; the overall construction can be made compact in size; and the thickness can be uniformly maintained in the axial direction so that satisfactory damping characteristics can be attained. Furthermore, both the side surfaces of the outer race can be prevented from sticking to its casing.